RE: Xen and the art of Database performance


--- "McDougall, Marshall (FSH)"
<Marshall.McDougall@xxxxxxxxx> wrote:

-----Original Message-----
From: redhat-list-bounces@xxxxxxxxxx
[mailto:redhat-list-bounces@xxxxxxxxxx] On Behalf
Of J.
Refugio Rodriguez
Sent: Wednesday, October 24, 2007 2:59 PM
To: General Red Hat Linux discussion list
Subject: Re: Xen and the art of Database
performance


--- "McDougall, Marshall (FSH)"
<Marshall.McDougall@xxxxxxxxx> wrote:

A while back we took delivery of several Dell
2950
servers to update our
hardware environment which supports our Ingres,
Sybase and DB2 systems.
Ingres 2.6 and DB2 were running on RHEL 2.1,
Sybase
was running on
RHEL3. We were hoping to be able to maintain the
same levels software,
but the new hardware is not supported by RHEL2.1.

This is where the fun
starts. I built up several RHEL4 servers and
installed the Database
systems on them and gave them to the DBA's to
test.
They promptly came
back and said that they were up to 7 times slower
than the previous
hardware platforms, with the exception of DB2. I
ran some OS benchmarks
and they came back up to 7 times faster than the
previous hardware. We
worked on various tweaks and tunes to the OS and
DBMS to no avail.
At that point we started to engage the
vendors/support orgs for the
various products. Sybase could do nothing to
improve performance on the
RHEL4 server, so we tried RHEL5(or advanced
platform
or whatever they
are calling it this week). The performance was
just
as dismal. We ended
up going back to RHEL3U9 to get the Sybase
environment to an acceptable
performance level.
Ingres is another story. First they said try
Ingres
2006. It worked,
but it has significant implications to our
OpenRoad
development
environment, and as such is not really an option.
I
went the same route
as before with the various flavours of RHEL and
it
made no difference.
Finally, I built a RHEL5 server, installed VMWare
Server, and created a
RHEL2.1 guest on that. We now have performance
where we want it. The
downside is that on my server with 8GB of ram I
can
only use 3.6GB for
the VM.
My options as I see them now are; Install VMWare
ESX
and see if that
buys me anything, or spend the time and effort to
see if Xen will be of
benefit. The problem with the latter is that
according to the doc RHEL
2.1 is not a supported OS on RH5.

Indeed, XenSource does not include the appropriate
modified kernel for RHEL 2.1 and, accordingly, is
not
officially supported on XenEnterprise 3.2 or
higher.

Notwithstanding, you can create an proper Linux
kernel
for your RHEL 2.1 by installing the same into a
machine that has the CPU virtualization extensions
(i.e., hardware assisted virtualization).

Once you successfully install/modify your RHEL 2.1
under XenEnterprise in the above hardware assisted
virtualization environment, you can use the image
on
older non-hardware assisted virtualization CPUs.

Before going to ESX, you may want to evaluate
XenEnterprise in price and performance. Back in
version 3.2 of XenSource XenEnterprise, you could
allocate to an virtual machine up to 15GB of
memory.

Disclaimer: Metztli Information Technology is an
Xensource Certified Partner.

So, after all this, the gist of my post is; Has
anybody successfully
sparked up a RHEL 2.1 guest, using more than 4 GB
of
RAM, on a RH5
virtual platform, or, has anyone installed Ingres
2.6 on a Linux 2.6
kernel and made it perform at an expected level?
Thanks for reading
this far.

Regards, Marshall
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Jose R Rodriguez
http://www.metztli-it.com


Thanks for the input Jose. It sounds like it's
doable with Xen, but it
also sounds like it's painful. Yesterday I
downloaded a time bomb trial
of ESX and had it and a RHEL2.1 VM running in about
1.5 hours. I've
taken a lot longer than that just trying to
understand the Xen docs that
I can find.

Regards, Marshall

Marshall,

It takes approximately 10 minutes to install the Linux
based XenServer into your physical server on the bare
metal. You then need to install the administration
console into another machine from where you will be
able to install, configure, and/or migrate live VMs as
your storage needs change.

Whereas XenSource XenServer 3.2 products were for
32-bit architecture, XenServer 4.0 has been updated to
64-bit.

The installation of your RHEL 2.1 is done as you did
under ESX, and the hardware requirements are similar,
i.e., both need hardware virtualization support. The
latter is found in hardware with Intel processors
shipped since the end of 2005 and hardware with AMD
equivalents that shipped since August 2006.

For a trial download of XenEnterprise (and/or a no
cost XenExpress download with VM guest support memory
allocation of up to 4GB): <
http://www.citrixxenserver.com/Pages/Download.aspx >

Documentation: <
http://docs.xensource.com/XenServer/4.0.1/ >

Knowledge base: < http://kb.xensource.com/kbindex.jspa


Support forums: <
http://forums.xensource.com/index.jspa >

You may also be interested in a feature similar to
Fedora 7, CentOS 5, and RHEL 5 VM manager:

"Red Hat Enterprise Linux 5 and SUSE Enterprise Linux
10 may be installed directly from vendor network
repositories using the vendor-provided Xen kernels,
and thus no longer require hardware-assisted
virtualization during the installation process."

(Please see the release notes <
http://docs.xensource.com/XenServer/4.0.1/releasenotes/releasenotes.html
)

Best regards.

Jose R Rodriguez
http://www.metztli-it.com

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